1. Technical Field
The present invention relates in general to an improved method for manufacturing sliders for magnetic recording heads, and in particular to the reactive ion etching (RIE) of the air-bearing surface (ABS) and/or trailing edge of the slider. Still more particularly, the present invention relates to the use of RIE over the entire slider or with the slider masked in order to change the topography of the trailing edge and remove protrusions that cause head crash.
2. Description of the Related Art
Digital magnetic recording devices for data storage generally comprise a thin film magnetic recording disk and a head which is moved above the surface of the rotating disk to electromagnetically read and write information on the disk. Advanced thin film magnetic recording disks generally comprise a rigid substrate, a magnetic layer such as a cobalt-based metal alloy, a protective amorphous carbon layer and a lubricant layer, such as perfluoropolyether disposed on the carbon overcoat.
During operation of the disk drive system, an actuator mechanism moves the magnetic transducer to a desired radial position on the surface of the rotating disk where the head electromagnetically reads or writes data. Usually, the head is integrally mounted in a carrier or support referred to as a xe2x80x9csliderxe2x80x9d. The slider is generally rectangular in shape and consists of two portions: a substrate portion and a head portion formed on an end face of the slider portion. Typically, this end face of the slider will constitute the slider trailing edge when the slider is suspended adjacent to a rotating recording disk.
The substrate portion of the slider can be made from ceramic material such as Al2O3/TiC, silicon carbide, zirconium oxide, or other suitable material. The head portion of the slider is typically a thin layer of alumina (Al2O3), or alumina overcoat, formed on the trailing edge face of the slider in which the magnetic portion of the head is embedded. Head elements such as poletips and shields and MR heads are imbedded into the head, these elements being made from metals and/or alloys of metals such as NiFe. The slider generally serves to mechanically support the head and any electrical connections between the head and the rest of the disk drive system. The slider is aerodynamically shaped to glide over moving air in order to maintain a uniform distance from the surface of the rotating disk, thereby preventing the head from undesirable contacting the disk.
Typically, a slider is formed with an aerodynamic pattern of protrusions (air bearing design) on its air bearing surface (xe2x80x9cABSxe2x80x9d), or substrate surface, which enables the slider to fly at a constant height close to the disk during operation of the disk drive. The recording density of the magnetic disk drive system is dependent upon the distance between a transducer and the magnetic media. One goal of the air bearing slider design is to xe2x80x9cflyxe2x80x9d a slider as closely as possible to a magnetic medium while avoiding physical impact with the medium. Smaller spacings, or xe2x80x9cfly heightsxe2x80x9d, are desired so that the transducer can distinguish between the varying magnetic fields emanating from closely spaced regions on the disk.
However, the benefit of closer spacing is contrasted by the adverse effect on the mechanical reliability of the slider. As the distance between the slider and the disk decreases, as it does with every generation of storage device, the probability of contact between the two surfaces increases, thus leading to unreliable data transfer and head crashing. The probability of contact between the slider and disk increases when any part of the trailing edge protrudes above the air bearing surface of the slider. Ideally, the read elements should be flush with the alumina material making up the slider surface. Thus, the precise topography surrounding the transducers is vital to the performance of the slider read/write head.
The trailing edge topography of a slider depends upon the lapping process and the overcoat material used. Furthermore, the heating of the head during operation causes thermal expansion of the organic insulation material in the head. This thermal expansion will cause a protrusion of overcoat material beyond the air bearing surface. It is not uncommon for an undesirable protrusion to be present when the head is flying over a disk. Since the protrusion is known to be detrimental to the operation of low-fly gliders, it would be beneficial to tailor the trailing edge profile to any defined shape.
The prior art discloses a general method of using Reactive Ion Etching (RIE), wherein some substrate is exposed to a reactive plasma in order to react the substrate surface species with the plasma and effectuate removal of the surface species. For example, Hsiao et al, Electrochemical Society Proceedings, Vol. 96, No. 12 (1996) shows that RIE plasmas will react with SiO2 differentially relative to Al2O3. However, no method of altering the topography of a slider using RIE is known in the art. The present invention is directed towards such means of tailoring a trailing edge profile through the use of RIE, in particular when SiO2 is used as an overcoat on the slider and alumina (Al2O3) is the undercoat.
It is therefore one object of the present invention to provide a method of altering the topography of the ABS or trailing edge of a slider or wafer of sliders, and/or to remove protrusions on the slider trailing edge.
It is another object of the present invention to provide a method of decreasing the likelihood of physical contact between a moving disk and the magnetic recording heads of the slider by providing an improved slider.
It is yet another object of the present invention to improve the thermal asperity characteristics of the magnetic recording heads of a slider.
It is yet another object of the present invention to provide for a process of selectively removing the SiO2 overcoat on a slider ABS.
The foregoing objects are achieved as is now described, wherein reactive ion etching (RIE) of low bombardment energy is used to alter the topography of a ABS or trailing edge of a slider or row of sliders, the slider having a substrate surface, at least one magnetic recording head imbedded in an SiO2 overcoat, and a vertical axis relative to the substrate surface. The steps include first applying a SiO2 overcoat at the wafer level to form the SiO2 trailing edge at the slider level. Following this step, the wafers are sliced into rows containing multiple sliders. Next, the rows are lapped. The rows are then placed on an electrode pallet, exposing the ABS or trailing edge to a plasma. The plasma is generated using an etchant gas such as a fluorine compound, e.g. SF6, CF4, etc., in combination with Argon and/or other etchant gases. The trailing edge (or trailing edges) are then exposed at least once to the RIE plasma for a predetermined time. The RIE angle is typically about 90xc2x0.
The above as well as additional objectives, features, and advantages of the present invention will become apparent in the following detailed written description.